Anthropic preparing to roll Claude Mythos into Claude Code and Claude Security - 'claude-mythos-1-preview' toggle briefly appeared publicly

Anthropic appears to be preparing the public rollout of Claude Mythos - the restricted security-focused frontier model that uncovered 10,000 high or critical vulnerabilities in its first month under Project Glasswing. References to 'claude-mythos-1-preview' have briefly appeared in the public Claude Code and Claude Security products, with at least one user reportedly seeing a toggle to enable Mythos before it was pulled. Anthropic originally announced Mythos in early preview on April 7 and held back the public release pending guardrails, warning the model 'can automatically develop functional cyberattacks at a highly professional level.' Pricing and tier availability are not yet disclosed.

Check

If you use Claude Code or Claude Security, watch for the Mythos toggle to appear. Review your Claude Max/Pro/Team subscription tier and any organizational data-handling policies for AI-coding tools.

Affected

Any organization using Claude Code or Claude Security where users may surface critical-severity flaws in supplier or open-source code that have not yet been responsibly disclosed.

Fix

Define an internal disclosure policy for Mythos findings before enabling broadly. Coordinate with the Anthropic Cyber Verification Program. Pair Mythos usage with patch-cycle compression on internet-facing services.